views/pdo_cache_backend.php

   1 <?php
   2 // Hoplite
   3 // Copyright (c) 2013 Blue Static
   4 //
   5 // This program is free software: you can redistribute it and/or modify it
   6 // under the terms of the GNU General Public License as published by the Free
   7 // Software Foundation, either version 3 of the License, or any later version.
   8 //
   9 // This program is distributed in the hope that it will be useful, but WITHOUT
  10 // ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11 // FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  12 // more details.
  13 //
  14 // You should have received a copy of the GNU General Public License along with
  15 // this program.  If not, see <http://www.gnu.org/licenses/>.
  16
  17 namespace hoplite\views;
  18
  19 require_once HOPLITE_ROOT . '/views/cache_backend.php';
  20
  21 /*!
  22   An instance of CacheBackend that stores compiled templates in a database
  23   table accessed through a PDO object.
  24 */
  25 class PDOCacheBackend implements CacheBackend
  26 {
  27   /*! @var \PDOStatement Used to query for cached templates. */
  28   protected $fetch_statement = NULL;
  29
  30   /*! @var \PDOStatement Used to insert new templates. */
  31   protected $insert_statement = NULL;
  32
  33   /*! @var \PDOStatement Used to expire out-of-date templates. */
  34   protected $delete_statement = NULL;
  35
  36   /*!
  37     Constructor that prepares the database statements.
  38
  39     @param \PDO The connected database object.
  40     @param string Name of the database table to store templates in.
  41     @param string Column in which the template name is stored.
  42     @param string Column in which the template data is stored.
  43     @param string Column in which the template last modified time is stored.
  44   */
  45   public function __construct(\PDO $db,
  46                               $table_name,
  47                               $name_column_name = 'name',
  48                               $data_column_name = 'template',
  49                               $timestamp_column_name = 'timestamp')
  50   {
  51     $this->fetch_statement = $db->Prepare("
  52         SELECT `$data_column_name` AS template,
  53             `$timestamp_column_name` AS timestamp
  54         FROM $table_name
  55         WHERE `$name_column_name` IN (:name)
  56     ");
  57
  58     $this->insert_statement = $db->Prepare("
  59         INSERT INTO `$table_name`
  60             (`$name_column_name`, `$data_column_name`, `$timestamp_column_name`)
  61         VALUES
  62             (:name, :template, :timestamp)
  63     ");
  64
  65     $this->delete_statement = $db->Prepare("
  66         DELETE FROM `$table_name`
  67         WHERE `$name_column_name` = :name
  68     ");
  69   }
  70
  71   public function GetTemplateDataForName($name, $modification_time)
  72   {
  73     if (!$this->fetch_statement->Execute(array('name' => $name)))
  74       return NULL;
  75
  76     $tpl = $this->fetch_statement->FetchObject();
  77     if (!$tpl)
  78       return NULL;
  79
  80     if ($tpl->timestamp < $modification_time) {
  81       $this->delete_statement->Execute(array('name' => $name));
  82       return NULL;
  83     }
  84
  85     return $tpl->template;
  86   }
  87
  88   public function StoreCompiledTemplate($name, $modification_time, $data)
  89   {
  90     $this->insert_statement->Execute(array(
  91         'name'      => $name,
  92         'timestamp' => $modification_time,
  93         'template'  => $data,
  94     ));
  95   }
  96 }